An internal combustion engine of a vehicle may be operated during conditions where ambient humidity levels are high. Humid air may be drawn into the engine while the engine is operating and the engine may perform well because higher temperatures in the engine allow water vapor to remain entrained in air. The higher humidity air acts as a charge diluent and it may be useful to reduce engine knock and NOx emissions. However, if the water vapor is allowed to condense within the engine, it may cause the engine to misfire. Engine emissions and performance may degrade if the engine misfires due to water condensing within the engine.
Water vapor may have a better chance of condensing in the engine if the engine is stopped. In particular, humid air drawn into the engine while the engine was operating may cool after the engine is deactivated. Cooling the humid air may lead to condensation within the engine and formation of water droplets within the engine and the engine air intake system. If the engine is started with water in the engine and/or in the engine air intake, the water may be drawn into engine cylinders via vacuum where it may cause the cylinders to misfire. Therefore, it may be desirable to provide a way of reducing the possibility of liquid water from being drawn into engine cylinders.
The inventor herein has recognized that the challenges associated with operating an engine during humid ambient conditions and has developed an engine operating method, comprising: activating a laser ignition system of an engine and vaporizing water within a cylinder via the laser ignition system in response to an engine start prediction; and rotating the engine in a reverse direction in response to the engine start prediction.
By vaporizing water that may form in an engine cylinder due to condensation, it may be possible to provide the technical result of improving engine starting via reducing the possibility of misfire within the engine. A laser ignition system may be activated in response to a predicted engine start to vaporize water that may be present in engine cylinders. The engine starting prediction may be based on a key fob or other device being within a prescribed distance of the vehicle. Alternatively, the engine start prediction may be based on an opening of a vehicle's door or via a remote vehicle start request.
The approach that is described herein includes several advantages. In particular, the approach may reduce engine emissions. Further, the approach may provide improved combustion during engine starting leading to smoother engine torque production during engine starting. In addition, the approach may improve engine restarts after an engine has been automatically stopped.
It should be understood that the summary above is provided to introduce in simplified form a selection of concepts that are further described in the detailed description. It is not meant to identify key or essential features of the claimed subject matter, the scope of which is defined uniquely by the claims that follow the detailed description. Furthermore, the claimed subject matter is not limited to implementations that solve any disadvantages noted above or in any part of this disclosure.